Heinrich Himmler was one of the most notorious leaders of Hitler's Nazi Party, responsible for the deaths of millions of men, women and children. Excerpts from chilling letters he wrote family were recently published on the German news site Die Welt.

In one letter, among hundreds of excerpts made public, Himmler sounds more like a traveling businessman than the leader of the SS and architect of the Third Reich's final solution.

"In the next few days I'll be in Lublin, Zamosc, Auschwitz, Lviv and then in the new quarters. I'm curious if and how I will be able to phone, it will probably be around 2000 kilometers to Gmund. All the best, have a nice trip and enjoy your days with our little daughter. Many warm greetings and kisses! Your Daddy."

At least 1.1 million people were killed at Auschwitz. PBS reports 90 percent were Jewish.

The letters were originally taken from Himmler's home in 1945, according to McClatchy. Die Welt, McClatchy explains, was recently given access by the maker of a forthcoming documentary film about Himmler.

In another letter to his wife, Himmler writes, "I'm off to Auschwitz. Kisses, Yours, Heini." Another offers a glimpse at the man's hatred. “A Jew will always be a Jew! ... But don't get worked up about the Jews, dear, dear woman, if I could only help you,” the letter reads, according to McClatchy.

Other recently published letters reveal Himmler and his wife, Marga, apparently referred to sex as "Revenge."

From the Daily Mail:

"I’m for nothing but 'Revenge' all the time," he wrote to Marga in January 1928, when he was on a train to Munich. "Remember 'Revenge,'” Marga insisted in April that year. "My black soul is thinking up the most impossible things."

The U.K.'s Telegraph spoke to Jacques Schuster, a German jourmalist who authenticated the documents.

From the Telegraph:

“It was interesting for me to see that Himmler was not Dr Jekyll and Mr Hyde. He had components of both in his personality — he was a private man, but a mass murderer also, often in the same moment. For example, there’s some days on which he said 'ok, today, I celebrate my birthday with kids, and in the afternoon I have to go Auschwitz’,” he said.

Himmler never wrote of his role in the Holocaust. The writers of Die Welt summarized his writings as the thoughts of a "clearly cold, feeling-less, self-righteous bureaucrat," according to NPR.